Hurst Dam – Yorkshire Dragonfly Group

Emerald Damselfly Lestes sponsa

Posted on 22 April 2007 by Paul Ashton

Length

35-39mm; Wingspan: Male 42mm; Female 45mm; Hindwing 19-22mm

Male

Metallic green in colour. This species has a slow maturation period of two to four weeks, over this period a blue pruinescence appears on the thorax between wings and segments 1,2, 9 and 10. Eyes blue. Confusion species is Scarce Emerald Damselfly which is extinct in Yorkshire. Both sexes rest with wings half open.

Female

Metallic green, with pale beige sides to the thorax. Distinctly thicker abdomen than male.

Behaviour

Weak flyer usually remaining close to emergent vegetation, rarely going far over water. Copulation usually takes place close to breeding site and last from 30 minutes to over an hour. Females usually arrive to oviposit in tandem with the male. Oviposits in to stems of emergent grasses, rushes, sedges and horsetails, usually above surface, but can submerge, including the male. Fairly sedentary and can be absent from seemingly good sites.

Habitat

Still or slow moving water such as ponds, bogs, ditches, canals and lake edges with dense emergent vegetation. Tolerates brackish and acidic water. Sensitive to excessive clearance of emergent vegetation.

Flight Period

Status

Found at many sites through all Vice-counties.

Distribution Map

Locations

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Blue-tailed Damselfly Ischnura elegans

Posted on 22 April 2002 by Paul Ashton

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Length

29-34mm; Wingspan: 35-40mm; Hindwing 14-21mm

Male

Dark bronze-black metallic with blue segment 8. Blue or green sides to the thorax and antehumeral stripes. Blue eye spots. Pterostigma is distinctive being bi-coloured black and white. Tips of the lower appendages diverge.

Female

Occur in several colour forms dependent on age. Segment 8, though not always blue, is usually clearly different from the other sections. Start as either rufescens with a reddish-pink thorax and blue segment 8 or violacea with a violet thorax and antehumeral stripes, black humeral stripes and blue segment 8. After around eight days they mature and change colour, rufescens become greenish-brown of the form rufescens-obsoleta. The form violacea mature into two separate from. The first is infuscans which is a pale green colour, and retaining the black humeral stripes. The second is an andromorph form which adopts the same colours as a male.

Behavior

Often found in marginal vegetation in large numbers. Copulation last from between two to six hours, due to this, it is the most frequently observed species seen in the wheel position. Often females selected by the males are still in their immature colour forms. Females oviposit alone onto the tissue of aquatic plants and debris, where they are not usually harassed by the males. Frequently found in dull weather when other species are inactive. Larvae emerge after one to two years.

Habitat

Wide range including garden ponds, lakes, rivers, canals and ditches. Can also be found in brackish conditions and acidic peaty pools. More tolerant of pollution than other species, only really avoiding fast-flowing water. Readily disperses and is one of the first species to colonise new sites.

Flight Period

Status

Common and widespread throughout the area.

Distribution Map

Locations

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Common Blue Damselfly Enallagma cyathigerum

Posted on 22 April 1999 by Paul Ashton

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Length

32mm, Wings 36-42mm

Male

Bright blue body with black markings on upper surface of abdomen, segment 2 has lollipop mark; segment 8 and 9 all blue; broad antehumeral stripes on black thorax; eye spot linked by bar.

Female

3 colour forms:-
1) abdomen with black markings.
2) Green with black markings.
3) Brown with black markings. All have characteristic medial spine under segment 8, presumably puncturing plant material before inserting an egg.

Habitat

Large ponds and lakes are the main preference for this species. Can also be found along canals and rivers, but will also tolerate brackish conditions. The most abundant Zygoptera found in open areas.

Behavior

The most dominant species on large lakes and reservoirs, swarming over the waters surface far from the banks in sunny conditions. Readily settles on emergent vegetation and is aggressive towards others, even driving away larger species. Copulation lasts for around 20 minutes, frequently away from water. Oviposits into submerged and emergent vegetation, usually in tandem. If the female submerges the male will uncouple, guarding the area waiting for her to re-emerge. Females can submerge for up to an hour. Larvae live amongst submerged vegetation emerging after 1-3 years. They mature in surrounding areas over a period of around 12 days.

Flight Period

Status

Occurs on a wide range of varying water-bodies. Can be more conspicuous than the similar Azure Damselfly. Blue damselflies ranging far over open water are usually this species. Generally the most abundant blue damselfly at sites, where the Azure can be absent.

Distribution Map

Locations

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Common Hawker Aeshna juncea

Posted on 22 April 1997 by Paul Ashton

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Length

74mm, Wings 95mm.

Males

Thorax top is black , narrow yellow antehumeral stripes and sides are brown with 2 narrow yellow thoracic stripes; abdomen black with pairs of yellow and blue spots including segments 9 and 10; legs black; wings have brilliant yellow costa.

Females

Thorax brown; abdomen brown with paired yellow spots, sometimes green, rarely blue. Leading edge of the wing yellow.

Habitat

Prefers acidic conditions, consisting of bog pools, ponds and lake margins on moorland and heathland. Will also use slow-flowing sections of upland streams. Requires areas of emergent vegetation to breed.

Behavior

Males are territorial, regularly chasing off intruders of any species. They are relentless flyers and can often be found active in dull conditions. Copulation takes from 60-75 minutes, with pairs usually settling amongst the heather, shrubs or trees. The female oviposits alone, inserting the eggs into submerged vegetation. Oviposition may take place in dull weather, when the first sign of activity is the sound of rustling wings in low vegetation. Larvae develop over a period of two or more years amongst the submerged vegetation. They emerge, usually at night, on emergent plant stems. They regularly wander away from breeding sites to feed in sheltered areas, such as woodland rides.

Flight Period

Distribution Map

Locations

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Black Darter Sympetrum danae

Posted on 22 April 1977 by Paul Ashton

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Length

32mm, Wings 47mm

Males

Narrow waist on black abdomen with golden spots segment 1 and 2, 8 and 9; thorax 2 yellow bars on side, 1 of black panels has 3 yellow spots; legs black.

Females

Yellow with black triangle top of thorax; legs black.

Behaviour

Males are not very territorial, with large numbers being present at some sites. Males hover over emergent vegetation, seeking females to mate with. They will frequently settle, especially on open ground and stones. In hot weather they will rest in the obelisk position, with abdomen pointing upwards, to reduce the surface area presented to the sun. Copulation lasts for several minutes, with oviposition taking place in tandem or alone. Oviposition takes place either directly into water, or into mud and mats of vegetation. Larvae emerge after one year and can survive the temporary drying out of their habitat.

Habitat

Mainly heaths containing boggy pools, peaty ponds and lakes with abundant emergent rushes and sedges. Sheltered sites produce the highest numbers. Sometimes disperses into atypical locations.

Flight Period

Distribution Map

Locations

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